Wyniki wyszukiwania - Biblioteka Nauki

1

Specjalizacja w dziedzinie fizyki medycznej – rafy, na jakie natrafiamy. Część 2

100%

Kukołowicz P.

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tom Vol. 9, nr 6

431--432

PL

W poprzednim numerze „Inżyniera i Fizyka Medycznego” zamieściłem pierwszy zbiór zadań przygotowujących do egzaminu specjalizacyjnego w dziedzinie fizyka medyczna. Mam nadzieje, że rozwiązanie tych zadań, osobom przygotowującym się do egzaminu, nie sprawiło żadnych problemów. W tym numerze czasopisma, ostatnim numerze roku 2020, zamieszczam kolejnych dziesięć zadań. Powodzenia!

2

Determination of the CTV-PTV margin for prostate cancer radiotherapy depending on the prostate gland positioning control method

63%

Sobajtis A. , Kukołowicz P.

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2020

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tom Vol. 26, Iss. 4

169--179

EN

Objective: The objective of the study was to determine the correct CTV-PTV margin, depending on the method used to verify the PG position. In the study, 3 methods of CBCT image superimposition were assessed as based on the location of the prostate gland (CBCT images), a single gold marker, and pubic symphysis respectively. Materials and methods: The study group consisted of 30 patients undergoing irradiation therapy at the University Hospital in Zielona Góra. The therapy was delivered using the VMAT (Volumetric Modulated Arc Therapy) protocol. CBCT image-based superimposition (prostate-based alignment) was chosen as the reference method. The uncertainty of the PG positioning method was determined and the margin to be used was determined for the CBCT-based reference method. Then, changes in the position of the prostate gland relative to these determined using the single marker and pubic symphysis-based methods were determined. The CTV-PTV margin was calculated at the root of the sum of the squares for the doubled value of method uncertainty for the CBCT image-based alignment method and the value of the difference between the locations of planned and actual isocenters as determined using the method of interest and the CBCT-based alignment method for which the total number of differences accounted for 95% of all differences. Results: The CTV-PTV margins to be used when the prostate gland is positioned using the CBCT imaging, single marker, and pubic symphysis-based methods were determined. For the CBCT-based method, the following values were obtained for the Vrt, Lng, and Lat directions respectively: 0.43 cm, 0.48 cm, 0.29 cm. For the single marker-based method, the respective values were 0.7 cm, 0.88 cm, and 0.44 cm whereas for the pubic symphysis-based method these were 0.65 cm, 0.76 cm, and 0.46 cm. Conclusions: Regardless of the method, the smallest margin values were obtained for the lateral direction, with the CBCT-based method facilitating the smallest margins to be used. The largest margins were obtained using the single marker-based alignment method.

3

Co to jest izocentrum mechaniczne przyspieszacza liniowego?

51%

Kukołowicz P. , Szałkowski D. , Tarchalski M.

Inżynier i Fizyk Medyczny

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2023

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tom Vol. 12, nr 2

125--127

PL

Niniejsza publikacja powstała w związku z projektem realizowanym przez NaviRation sp. z o.o. wraz z Narodowym Instytutem Onkologii w Warszawie. Celem projektu jest stworzenie i wdrożenie do użytku urządzenia do precyzyjnego wyznaczania izocentrum mechanicznego przyspieszacza liniowego oraz połączenia tej informacji z informacją o izocentrum promieniowania. Jakkolwiek fizycy medyczni, analizując różne zagadnienia związane z dozymetrią promieniowania i radioterapią, bardzo często używają pojęcia „izocentrum”, to jednak bardziej wnikliwa analiza tego, czym jest izocentrum, pokazuje, że izocentrum może być definiowane na kilka różnych sposobów. Po pierwsze dlatego, że można mówić o kilku izocentrach: o izocentrum mechanicznym, izocentrum promieniowania, izocentrum obrazowania. Po drugie izocentrum, rozumiane jako oś obrotu, nie określa pewnego punktu w przestrzeni, stałego względem zewnętrznego układu współrzędnych. Jak to zwykle bywa, z daleka wiele rzeczy wygląda na jednorodne, dość łatwo dające się zdefiniować. Gdy zbliżamy się do badanego obiektu, dostrzegamy, że ma strukturę, pewne cechy, które wymagają bardziej szczegółowego opisu. Podobnie jest z izocentrum. Nie trywialność zagadnienia znalazła swoje odzwierciedlenie w bardzo wielu różnych metodach pomiaru izocentrum [1]. W tej publikacji podzielimy się naszym spojrzeniem na pojęcie izocentrum, koncentrując się na izocentrum mechanicznym przyspieszacza liniowego.

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Wyznaczanie jednorodnych dawek równoważnych dla pacjentów leczonych techniką Simultaneous Integrated Boost

51%

Araszkiewicz M. , Korgul A. , Kukołowicz P.

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tom Vol. 9, nr 3

159--160

PL

Celem radioterapii jest dostarczenie zaplanowanej dawki promieniowania do targetu przy jednoczesnym zminimalizowaniu dawki deponowanej w narządach krytycznych. Istnieją przypadki, gdzie w planie leczenia jednego pacjenta uwzględniono kilka obszarów tarczowych (ang. Planning Target Volume – PTV). Jedną z możliwych technik napromieniania jest wtedy tzw. technika Simultaneous Integrated Boost (SIB). Polega ona na jednoczesnym napromienianiu różnymi dawkami więcej niż jednej objętości tarczowej. Ze względu na konieczność jednoczesnego podania dawek w kilku targetach otrzymują one dawkę różną od zleconej. W pracy, stosując koncepcję jednorodnej dawki równoważnej (ang. Equivalent Uniform Dose – EUD), oceniono wzajemny wpływ dawek deponowanych w poszczególnych targetach.

EN

Radiotherapy aims to deliver an appropriate dose of ionizing radiation to the target, minimizing the doses in critical organs. There are cases where several Planning Target Volume (PTV) are planned in the treatment plan for one patient that require different doses to be deposited. In such cases, one of the possible irradiation techniques is the so-called Simultaneous Integrated Boost (SIB) technique, in which all PTV are simultaneously irradiated with different doses. Due to the existing Beam Penumbra Effect, the application of a dose in one PTV affects the doses in the second PTV receiving a lower dose. In this paper, using the concept of the Equivalent Uniform Dose – EUD (EUD) the mutual influence of doses deposited in particular PTVs was assessed.

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Evaluation of SRS MapCHECK with StereoPHAN phantom as a new pre-treatment system verification for SBRT plans

51%

Sadowski B. M. , Fillmann M. , Szałkowski D. , Kukołowicz P.

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2022

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tom Vol. 28, Iss. 2

84--89

EN

Introduction: The aim of this study was to evaluate the new 2-Dimensional diode array SRS MapCHECK (SunNuclear, Melbourne, USA) with dedicated phantom StereoPHAN (SunNuclear, Melbourne, USA) for the pre-treatment verification of the stereotactic body radiotherapy (SBRT). Material and methods: For the system, the short and mid-long stability, dose linearity with MU, angular dependence, and field size dependence (ratio of relative output factor) were measured. The results of verification for 15 pre-treatment cancer patients (5 brains, 5 lungs, and 5 livers) performed with SRS MapCHECK and EBT3 Gafchromic films were compared. All the SBRT plans were optimized with the Eclipse (v. 15.6, Varian, Palo Alto, USA) treatment planning system (TPS) using the Acuros XB (Varian, Palo Alto, USA) dose calculation algorithm and were delivered to the Varian EDGE® (Varian, Palo Alto, USA) accelerator equipped with a high-definition multileaf collimator. The 6MV flattening-filter-free beam (FFF) was used. Results: Short and mid-long stability of SRS MapCHECK was very good (0.1%-0.2%), dose linearity with MU and dependence of the response of the detector on field size results were also acceptable (for dose linearity R2 = 1 and 6% difference between microDiamond and SRS MapCHECK response for the smallest field of 1 × 1 cm2). The angular dependence was very good except for the angles close to 90° and 270°. For pre-treatment plan verification, the gamma method was used with the criteria of 3% dose difference and 3 mm distance to agreement (3%/3 mm), and 2%/2 mm, 1%/1 mm, 3%/1 mm, and 2%/1 mm. The highest passing rate for all criteria was observed on the SRS MapCHECK system. Conclusions: It is concluded that SRS MapCHECK with StereoPHAN has sufficient potential for pre-treatment verification of the SBRT plans, so that verification of stereotactic plans can be significantly accelerated.

6

Podyplomowe szkolenie fizyków medycznych – i co dalej?

51%

Kukołowicz P. , Piotrowski T. , Kidoń J.

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2022

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tom Vol. 11, nr 5

371--372

PL

Ustawa Prawo Atomowe z 2019 roku określiła nowy rodzaj ścieżki rozwoju fizyków medycznych. Obok istniejącej od 2005 roku specjalizacji w dziedzinie fizyki medycznej dodała możliwość uzyskania tytułu fizyka medycznego „w zakresie”. Fizykiem medycznym w zakresie medycyny nuklearnej można zostać po ukończeniu kursu zgodnego z programem opracowanym przez Centrum Medyczne Kształcenia Podyplomowego w porozumieniu z konsultantem krajowym w stosownej dziedzinie lub po ukończeniu modułu ogólnego i modułu z medycyny nuklearnej (zgodnie z programem szkolenia specjalizacyjnego prowadzonego przez jednostkę posiadającą akredytację do prowadzenia szkolenia specjalizacyjnego w dziedzinie fizyki medycznej w rozumieniu przepisów ustawy z dnia 24 lutego 2017 r. o uzyskiwaniu tytułu specjalisty w dziedzinach mających zastosowanie w ochronie zdrowia).

7

Optical system for precise isocenter measurement

51%

Kukołowicz P. , Szalkowski D. , Jackowska-Zduniak B. , Tarchalski M.

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tom Vol. 29, Iss. 4

178--184

EN

Introduction: The geometrical precision of the machines is essential for effective and safe radiotherapy. Methods currently used for the measurement of the mechanical isocenter have many limitations. In this work, the optical system NaviRation for very precise measurement of mechanical accelerator isocenter is described. The results of the measurement of the isocenter for linear accelerator are also presented. Materials and methods: An optical system for measuring the accelerator isocenter was designed and built. The optical system consists of two cameras recording the target position made according to a patented Zeiss technology. About 1,200 pairs of images are recorded during the rotation of the gantry, collimator and treatment table. Mathematical analysis of these images makes it possible to determine the location of the target center during rotation. In order to verify the accuracy of the measurements, a device simulating rotational motion was designed. The measurement results were also verified at the Central Office of Measures. The system must be calibrated each time before taking measurements. In this article, we present the results of measurements for the Versa HD accelerator. Results: The accuracy of determining the current position of the axis of rotation was 0.15 mm. The time of taking measurements of all rotations does not exceed 20 minutes. Measurement results for the Versa HD accelerator showed that this accelerator met the criteria described by TG142 of the AAPM. The diameter of the gantry, collimator and table isocenter spheres were 1.5 mm, 0.3 mm and 0.4 mm, respectively. Conclusions: The system enables precise, fast and simple mechanical isocenter measurement of the gantry, collimator and treatment table. It is also possible to perform all tests related to the measurements of distances, e.g. quality control of distance indicator, and distance of the table movement. The isocenter is measured independently of the accelerator for which measurements are made.

8

Evaluating the impact of anatomical changes on dose distributions in head and neck cancer

51%

Sobajtis A. , Kukołowicz P. , Iwanowska-Chomiak B.

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2023

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tom Vol. 29, Iss. 3

156--164

EN

Introduction: Thanks to modern IGRT procedures, it is possible to track changes in the patient's anatomy and thus calculate the dose distribution for the current anatomical conditions of the patient. This allows the scheduled dose to be compared with the delivered dose. In the case of large discrepancies, it is possible to improve the treatment plan. Radiotherapy, during which the treatment plan is modified, resulting from changes in anatomy, is referred to as adaptive radiotherapy. Material and methods: This study was performed for 30 patients with H&N cancer at the University Hospital in Zielona Góra. All patients were treated with VMAT. The Simultaneous Integrated Technique was used. In each treatment session, set-up verification was performed. Alternating every other day, the CBCT and two orthogonal portal images were made, and position correction prior to each session was performed. For all patients, new planning CT was made after the 11th and 22nd treatment sessions. Dose distributions with the initial plan on CT11 and CT22 were calculated. The initial dose-volume histograms DVH0 were compared with dose-volume histograms DVH11 and DVH22 calculated on CT11 and CT22. Results: We compared the dose distribution in the CTVs and in the most important organs at risk obtained for initial anatomy and dose distributions calculated with the initial plan on the CTs performed after the second and the fourth week of irradiation. The differences between mean doses and V95% to GTV obtained for the initial CT and two other CTs were small. For a few CTs, the values of V95% were smaller by more than 5% points. In most patients, the mean dose in salivary glands increased during treatment. Conclusions: Anatomical changes occurring during radiotherapy in patients with head and neck cancers have little influence on the dose deposited in the Clinical Target Volume. Adaptive therapy may be of particular importance if relapse occurs and re-irradiation.

9

Independent verification of treatment planning system calculations

45%

Dąbrowska-Szewczyk E. , Zawadzka A. , Brzozowska B. , Walewska A. , Kukołowicz P.

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tom Vol. 66, No. 2

47--53

EN

Purpose: According to the available international recommendations, at least one independent verifi cation of the calculations of number of monitor unit (MU) is required for every patient treated by teleradiotherapy. The aim of this study was to estimate the differences of dose distributions calculated with two treatment planning systems: Eclipse (Varian) and Oncentra MasterPlan (Elekta). Materials and methods: The analysis was performed for 280 three-dimensional conformal radiotherapy treatment (3D-CRT) plans with photon beams from Varian accelerators: CL 600C/D X6 MV (109 plans), CL 2300C/D X6 MV (43 plans), and CL 2300C/D X15 MV (128 plans). The mean doses in the planning target volume (PTV) and doses at the isocenter point obtained with Eclipse and Oncentra MasterPlan (OMP) were compared with Wilcoxon matched-pairs signed rank test. Additionally, the treatment planning system (TPS) calculations were compared with dosimetric measurements performed in the inhomogeneous phantom. Results: Data were analysed for 6 MV plans and for 15 MV plans separately, independently of the treatment machine. The dose values calculated in Eclipse were significantly (p <0.001) higher compared to calculations of OMP system. The average difference of the mean dose to PTV was (1.4 ± 1.0)% for X6 MV and (2.5 ± 0.6)% for X15 MV. Average dose disparities at the isocenter point were (1.3 ± 1.9)% and (2.1 ± 1.0)% for X6 MV and X15 MV beams, respectively. The largest differences were observed in lungs, air cavities, and bone structures. Moreover the variation in dosimetric measurements was less as compared to Eclipse calculations. Conclusions: OMP calculations were introduced as the independent MU verification tool with the first action level range equal to 3.5%.

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Wyniki odtwarzalności ułożenia pacjentów napromienianych wiązkami zewnętrznymi w Centrum Onkologii – Instytucie w Warszawie w roku 2017

32%

Kukołowicz P. , Czuchraniuk P. , Kmita A. , Mazur M. , Jancewicz K. , Niebyłowska D. , Mazur W. , Przybyś A.

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tom Vol. 8, nr 2

127--130

PL

Kontrola odtwarzalności ułożenia jest istotnym elementem zapewnienia bezpieczeństwa radioterapii. Wykonywana u każdego leczonego pacjenta umożliwia zmniejszenie rozbieżności pomiędzy planem i jego realizacją. Analiza wyników kontroli ułożenia przeprowadzonych w dłuższym czasie umożliwia ogólną ocenę jakości napromieniania. W tej pracy przedstawiono, zgromadzone w 2017 roku, wyniki kontroli ułożenia w 5 jednorodnych grupach pacjentów leczonych z powodu nowotworów głowy i szyi, nowotworów piersi, nowotworów tkanek miękkich, przewodu pokarmowego górnego i nowotworów ginekologicznych napromienianych w Centrum Onkologii – Instytucie w Warszawie na Ursynowie. Kontrolę przeprowadzano w pierwszych trzech sesjach terapeutycznych. Wyniki są zaprezentowane w kategoriach błędów przypadkowych i systematycznych.

EN

The setup control is an important part of the quality assurance of the external radiotherapy. It enables diminishing the observed discrepancies between the treatment plan and its actualization. The analysis of the data of setup control collected in the radiotherapy department for the longer period of time enables the evaluation of the quality of the irradiation. In this article the results of setup control for the patients irradiated in the Memorial Maria Sklodowska-Curie Cancer Center Institute of Oncology, collected for the 5 locations (head&neck, breast, sarcomas, the upper digestive tract and gynecology) in 2017 year are presented. The setup control was performed in the first free treatment sessions. The results are presented in terms of random and systematic setup errors.